Spring-levered versus piezo-electric pedometer accuracy in overweight and obese adults

Purpose: The purpose of this study was to examine the effects of BMI, waist circumference, and pedometer tilt on the accuracy of a spring-levered pedometer (Yamax Digiwalker SW-200 (SW)) and a piezo-electric pedometer (New Lifestyles NL-2000 (NL)) during treadmill walking and over a 24-h period in overweight and obese adults. Methods: Forty participants (40 +/- 13.0 yr, 32.6 +/- 4.8 kg(.)m(-2)) walked on a treadmill at various speeds (54, 67, 80, 94, and 107 m(.)min(-1)) for 3-min stages. Simultaneously, an investigator determined actual steps by a hand counter. For all walking trials the SW and NL were positioned on the right and left waistband, respectively. Height, weight, pedometer tilt angle and circumference measures of the hi, and waist were also measure d, Thirty-six participants wore the pedometers for a 24-h period in the same position as during the treadmill walking trials. Results: In general, the SW became less accurate with increasing BMI, increasing waist circumference, and greater pedometer tilt, whereas the NL was not affected by these variables. The SW error scores were significantly correlated with the absolute pedometer tilt angle at all walking speeds (P < 0.05), but the NL error scores were not. On average the NL recorded 1030 +/- 1414 (16.5 +/- 22.7%) more steps that the SW during the 24-h trial. Conclusion: In overweight and obese individuals, a piezo-electric pedometer (NL) is more accurate than a spring-levered pedometer (SW), especially at slower walking speeds. In addition, it appears that pedometer tilt; more so than waist circumference and BMI, was the most important factor influencing the accuracy of the SW. The NL accuracy was not affected by pedometer tilt, waist circumference, or BMI.